Electro-optical system and apparatus



. V G. VANDER YEER DILLENBACK, JR

' ELECTRO-OPTICAL syswm AND APPARATUS Filed Oct; 26, 1936 WMWMMM;

m r INVENTOR ATTORNEY Patented May 32, 194.

EIECTRO-OPTICAL SYSTEM AND APPATUS Application October 2c, 1936, Serial No. 107,524

19 Claims.

This invention relates to electro-optical systems and more particularly to systems for trans-' mitting currents representing a visual representation over a service line, such for example as the usual telephone subscriber's telephone or telegraph line.

In certain cases, for example in newspaper work, it is often highly desirable to be able to transmit pictures or other visual representations from any one of a number of widely distributed points to a central reproducing station, over the nearest available telephone or telegraph line. However under existing conditions it is not feasible or permissible to connect the picture current transmitter to the service line in any way which would disturb the existing telephone apparatus or connections, either at the telephone exchange or at the local subscribers station.

Accordingly it is one of the principal objects of this invention to provide an arrangement whereby a picture current transmitter, or a picture current receiver, can be efiectively coupled to a telephone or similar service line without disturbing, changing or otherwise interfering with the normal functioning of the line or its associated apparatus.

A feature of the invention relates to an arrangement whereby the existing subscribers station apparatus, for example the usual telephone call box, can be used as a link to impress the picture or other signals on to the telephone line, or to receive signals from the tele phone line.

Another feature relates to the'novel organization, arrangement and relative location of parts which constitute a convenient and cheap method of impressing picture or other signal currents on a telephone or similar service line.

Other features and advantages not specifically enumerated will be apparent after a consideration of the following descriptions and the appended claims. In the drawing,

Fig. 1 is a composite schematic diagram of cirmeans of electric currents. It will be understood however that only those parts of the system which are necessary to a complete understanding of the invention are illustrated. Preferably although not necessarily the system is of the type illustrated in Patent No. 2,015,742, granted October 1, 1935, and embodies means to translate the shade characteristics of the picture into a corresponding current having a regular frequency such as a carrier current, and with amplitude variations determined by the picture characteristics. picture or other representation-l to be transmitted may be wrapped around a cylindrical drum 2 which may be rotated around its axis and simultaneously advanced by means of a leadscrew or the like. Inasmuch as scanning drums or carriers of many known types are familiar to the art further description thereof is not believed necessary herein. Preferably, although not necessarily, the drum 2 is driven from a synchronous motor 3 at the proper speed and also driven by motor 3 is an interrupter or chopper disc 4 having a series of perforations around its margin for purposes about to be described.

Associated with the scanning drum is a source 5 of steady light preferably capable of producing a concentrated spot of light. Positioned in front of source 5 is a suitable condensing lens system 6 by means of which the light from source 5 is projected in the form of a spot of elemental area upon the, picture I. Also associated with the scanning drum 2 is an objective lens for collecting the reflected light from the illuminated,

elemental area of the picture and focussing it upon the aperture in the apertured diaphragm 8. Suitably mounted adjacent the-aperture in diaphragm 8 is a light sensitive cell 9, preferably although not necessarily of the Elster-Geitel type. The electro-optical system is so arranged that the reflected light beam Ill passes through the marginal perforations in the rotating disc 4. Consequently as the picture is being scanned, there is produced in the output of cell 9 a current having a regular frequency determined by the number of times per second the disc 4 inter rupts the light beam l0, and this current will have instantaneous amplitude variations determined by the shade characterlstics of the suecessive elemental area of the picture I. Preferably the number of perforations in the disc 4 is chosen and the disc speed is such that the regular frequency current from the cell 9 is of an audio-frequency, for example 1300 cycles per second. The output of cell 9 will then be an Thus-as indicated in Fig. 1, the

audio-frequency carrier current modulated in accordance with the picture current signals. It will be understood of course that any other wellknown method of translating the picture shade characteristics into a correspondingly modulated audio-frequency carrier current may be employed.

It is well-known in the art of telephone communication that the induction coil in the usual telephone callv box when suitably energized produces stray electromagnetic fields which can be used to control the output of a high gain amplifler for the purpose of operating a recorder at a receiving station. If the process is to be reversed, that is if the telephone call box induction coil is to be used for impressing message signals on the telephone line it is merely necessary to employ suflicient power to overcome the losses in coupling. It is therefore desirable to make the coupling means between the signal transmitter and the induction coil in the telephone box as effective as possible. Some telephone boxes being of non-magnetic material such for example as Bakelite or wood permit a higher degree of efficiency in coupling than telephone boxes of sheet iron or the like. In any event the principle of operation is identical whether the induction coil is within a call box of iron or non-magnetic material or whether it is open to the air or unhoused, it being necessary merely to insure that the picture signals are translated into sufficient electromagnet energy so as to induce sufflcient voltages-.in the induction coil. Accordingly the photoelectric currents from cell 9 are amplified in a preamplifier I0 preferably of the vacuum tube type, and the output of this amplifier is further amplified to the desired level by means of successive stages represented by the numerals II and I2. stage i2 is connected to the windings l3, M of a suitable electromagnet l5 preferably having a laminated construction for purposes well-known in the electromagnet art. While the drawing The output of the final amplifier shows the windings i3 and M connected in series in the output circuit of tube l2 it will be obvious that a parallel connection of these windings may be employed.

Preferably the magnet 55 is so proportioned that the separation of the poles i6 and I! is such as to allow the magnet to be easily slipped over the usual telephone call box iii. In order to comply with the usual telephone requirements, the magnet I5 is not secured to or otherwise permanently attached to the box It. For this purpose, the magnet may be fastened to a board or other suitable support which may be placed in juxtaposition to box ill but without being fastened to the box. In some telephone boxes the induction coil is situated adjacent the top of the box and in others it is situated near the bottom of the box. It is quite obvious therefore that the magnet l5 should be so positioned with respect to box it as to provide the maximum electromagnetic coupling to the said induction coil, often, although not necessarily, with the poles of the magnet approximately coaxial with the induction coil. If desired the board or other support to which the magnet I5 is fastened may tion coil 2! in the call box 22 at the receiving station, and as is well-known these currents produce stray electromagnetic fields, the intensity of these stray fields depending upon the intensity of the received currents.

Associated with the telephone box 22 is an electromagnet 23 which may be similar to the magnet I5 and is provided with a pair of windings 24 and 25. The windings 24 and 25 are connected to the input circuit of a suitable multistage vacuum tube amplifler 26 the output of which is used to control the picture reproducing equipment 21 which may be of any well-known type such for example as disclosed in Fig. 2 of Patent No. 2,015,742. The stray fields from the induction coil 2| will therefore result in an obvious manner in corresponding amplified currents in the output of amplifier 26 whereby the picture may be reproduced in the equipment 21. It will be understood of course that the picture drum 2 is operated in synchronism with the corresponding drum or picture surface carrier provided in the equipment 21. Preferably this synchronism is achieved in the manner described in detail in said Patent No. 2,015,742. From the foregoing description, it will be seen that all that is necessary for one in the field to transmit a picture to a distance, is to couple the output of the picture transmitter by means of an electromagnet situated adjacent to the call-box of the nearest telephone subscriber's substation set. He thereupon secures a telephone connection with the desired distant point in the usual way by raising the receiver at his station from the switchhook and dialling or otherwise completing the connection to the called station. The

called party thereupon, or previously, has coupled his picture receiving equipment to the call box 22 after removing the receiver from its switchhook. If necessary the calling and called party may engage in telephonic conversation prior to starting the picture transmitting and reproducing equipment, since the telephone connection is not disturbed in any way for normal use.

Where the induction coil is located adjacent the bottom of the telephone call box a coupling magnet of the type shown in Fig, 2 may be employed, so that the poles of the magnet may be positioned adjacent the bottom of the box as shown. Instead of positioning the coupling magnet with its poles adjacent the sides of the telephone box, it may be positioned so that its poles face the rear 28 of the call box as shown in Fig. 3.- Likewise the magnet may merely rest on the top of the call box as shown in Fig. 4. It will be understood however that various changes and modifications may be made as will be obvious to those familiar with the art. For example while the magnet I5 is preferably supported on a member separate from the box, it will be obvious that it may be secured in any well-known manner on the telephone box and the supporting means may be adjustable to vary the relative position of magnets i5 and IQ for maximum coupling efficiency. Thus as shown in Figs. 1 to 4 the magnet core may be of laminated iron which as is well-known has a certain amount of springiness. Instead of designing the magnet l5 so that the spacing between the poles is slightly greater than the width of the telephone box as above-described, this spacing may be slightly smaller than the width of the telephone box so that the natural springiness of the laminations will cause the magnet to grip the sides of the box. If desired the magnet may be provided with an adjustable supporting rod 29 as shown in Fig. 2 so that the height of the magnet with respect to the box may be adjusted. Other means for adjustably securing the magnet on the telephone box will be obvious.

For example instead of relying on the natural springiness of the laminations of magnet l5 to grip the box, the magnet may be provided with an adjustable turnbuckle connecting the vertical legs of the yoke (Fig. 2) for adjusting the magnet on the box and for securing it in adjusted position.

What I claim is:

1. In combination, a telephone line having a subscriber station including a phone-box unit at opposite ends thereof, an induction coil in each phone-box unit connected in said line at each of said stations, a transmitter for generating a carrier wave modified by signals, inductance means coaxial with one of said induction coils for electrically inducing said generated signals into said line when said stations are in operative connection, means coupled with the other of said induction coils for picking-up said signals, and a receiver connected to said last-mentioned means to be operated by said picked-up signals.

2. In a system for transmitting electrical signals over a telephone line having a subscriber station with a phone-box and telephone receiver at each end thereof, means at one end of said line for generating a carrier wave modulated by signals to be transmitted, and means comprising a solenoid mountable on said phone-box and controlled by said signal-modulated carrier wave for generating an electrical field to electrically induce corresponding signals into one end of said telephone line, said last means being effective for inducing said signals only when the telephone receiver is moved to close the telephone circuit, and means for adjusting said solenoid for maximum efliciency in inducing said signals.

3. In a system for transmitting electrical signals over a telephone line having a subscriber station with a phone-box, means for generating a carrier wave modulated by signals to be transmitted, means comprising a solenoid secured to said box controlled by said signal-modulated carrier wave for generating an electrical field to an induction coil in each phone-box, means forgenerating a carrier wave modulated by signals to be transmitted, means controlled by said signal-modulated carrier wave for electromagnetically inducing corresponding signals into one end of said telephone line comprising a solenoid placeable on the phone-box at said first end of the telephone line and coaxial with its induction coil.

5. In a system for transmitting telephone and telegraph signals over a telephone service line,

one of said stations including a telegraph transmitter, said telegraph transmitter having means to generate a regular audio frequency tone current modulated by the telegraph signals, another of said substations including a telegraph recorder and a coupling coil inductively related to said induction coil thereat, said coupling coil being energized by said modulated audio frequency tone current, and means including said coupling coil and said tone current for controlling said telegraph recorder in accordance with the operation of said telegraph transmitter.

6. In a system for transmitting telephone and telegraph signals over a telephone service line, a telephone substation including a telephone transmitter, telephone receiver and a telephone induction coil connected to said line and normally used in transmitting telephone messages over said line, two auxiliary coils not normally used for telephone signal transmission but inductively related to said telephone induction coil, means to generate telegraph signals in the form of a regular audio frequency tone current modulated by the telegraph signals, and means to energize said auxiliary coils by said modulated tone current.

'7. The method of telegraphing over a telephone service system which comprises, generating telegraph signals in the form of a modulated regular tone audio frequency current, inducing said signals into an inductance coil forming a normal service component of the telephone substation equipment, and at a receiving telephone substation inductively transferring said signals from the normal telephone inductance coil thereat to a telegraph recorder.

8. The method of transmitting signals over a telephone line having a subscriber's telephone subset at opposite ends and without a direct connection to the telephone line conductors which includes, generating electric signals, employing said signals in producing a carrier current of regular audio frequency and electromagnetically inducing said modulated audio frequency current into a coil forming part of the telephone subscribers subset, without disturbing the normal electric service connections of said subset as used during normal telephone communication.

9. A system for transmitting signals over a telephone line having a subscriber's telephone subset at oppositeends thereof and without di rect connection to the telephone line conductors, which comprises means to generate electric signals in the form of a modulated carrier current of audio frequency, means to produce an electromagnetic field corresponding to said audio frequency carrier current, the last-mentioned coaxial line with said induction coil to obtain' optimum coupling condition.

11. A transmitter for telepicture systems comprising a telephone box for housing telephone apparatus of a telephone system including an induction coil connected in the telephone system, a pair of solenoids connected in parallel and secured to said telephone box, and means for inducing picture signals across said solenoids. 12. A transmitter for telepicture systems com prising a telephone box for housing telephone apparatus of a telephone system including an induction coil connected in the telephone system,

a pair of solenoids connected in parallel and secured to said telephone box, means for impressing picture signals in phase across said solenoids, and a common yoke for mechanically supporting said coils.

13. A transmitter for telepicture systems comprising a telephone box for housing telephone apparatus of a telephone system including an induction coil connected in the'telephone system,

a pair of solenoids connected in parallel and secured to said telephone box, means for impressing picture signals in phase across said solenoids, and a U-shaped yoke extending from one to the opposite side of said telephone box and secured thereto for supporting said solenoids.

14. A transmitter for telepicture systems comprising a telephone box ior housing telephone apparatus of a telephone system including an induction coil connected in the telephone system,

a solenoid secured to said telephone box and arranged to be coaxial with said induction coil, means for inducing picture signals across said solenoid, an iron core for said solenoid, and means for adjusting said solenoid axially with respect to the induction coil for optimum'coupling ad'- ingpicture signals in phase across said solenoids,

a common yoke for mechanically supporting said coils, and means for adjusting said solenoids axially with respect to the induction coil for optimum coupling adjustment.

17. A transmitter for telepicture systems comprising a telepicture box for housing telephone apparatus of a telephone system including an induction coil connected in the telephone system, a pair of solenoids connected in parallel and secured to said telephone box, means for impressing picture signals in phase across said solenoids, a U- shaped yoke extending from one to the opposite side oi said telephone box and secured thereto for supporting said solenoids, and means for adjusting said solenoids axially with respect to the induction coil for optimum coupling adjustment.

18. In a telepicture system employing a telephone line having a telephone box including an induction coil, electromagnetic means for coupling to said induction coil, means for securing said electromagnetic means on said telephone box, and means for adjusting said electromagnetic means in substantial coaxial relation with said induction coil for optimum coupling condition.

19. In combination with the bell box of a telephone substation, said box containing an induction coil, a u-shaped core member mounted on the cover of said box with the pole pieces thereof extending toward the ends of the core of said induction coil and means for energizing said core GARETT VANDER VEER DIILENBACK, JR. 

